For getting the update, and re-rooting, you can follow the guide I made here at this tread
, but you can probably skip down to Part C as long as the phone takes the update just fine, and Part D for the phone that already has the update. I only included the part about flashing a pure stock image because my phone wouldn't update all the way when I tried.
As for increasing the data speeds, this is a suggestion I found some time ago. Not sure how well it works, as I haven't noticed much of a difference, but then my data speeds have been pretty consistently quicker since the latest update.
First, you'll need to get a hold of your MSL number, if you don't have it already. I've found the easiest way is to download a Terminal Emulator from the Market, open it, and enter "getprop ril.MSL" (terminal emulator IS case-sensitive, just a heads-up). The emulator will display a six-digit number (and it's different for every phone); this is a kind of password for altering certain phone settings, so be sure to record it down, and keep it in a safe place.
Next, go to the phone dialer, and type ##3282#. As soon as you press the last #, it will open a "Data Programming" hidden menu. It may ask for the MSL here, but my phone usually doesn't. In the menu are two choices: View, and Edit. Press on Edit, and the phone will ask for the MSL at this point, regardless of whether it asked for it before or not. Enter the number you found from the terminal emulator, and now you'll be presented with five new options: "Data Profile", "EVDO", "Advanced", "USB Charging", and "Others". Be VERY CAREFUL with what you edit anywhere in this menu, as changing the wrong thing will cause the phone to no longer connect to data, at best. Select "Advanced, and at the top will be three options with "Vocoder" in the name. Tap on each one, and you'll be given a list of choices. Change each one to 4GV, press the back button to get back to the home screen, then reboot the phone. When it's back on, you should experience faster data speeds.
Hope this helps, and good luck